1. Field of Invention
The present invention relates to power conversion, and more particularly, to optimizing operation of a DC-to-AC power converter.
2. Description of Related Art
Power converters are essential for many modern electronic devices. Among other capabilities, power converters can adjust voltage level downward (buck converter) or adjust voltage level upward (boost converter). Power converters may also convert from direct current (DC) power to alternating current (AC) power, or vice versa. Power converters are typically implemented using one or more switching devices, such as transistors, which are turned on and off to deliver power to the output of the converter. Control circuitry is provided to regulate the turning on and off of the switching devices, and thus, these converters are known as “switching regulators” or “switching converters.” The power converters may also include one or more capacitors or inductors for alternately storing and outputting energy.
A DC-to-AC converter according to previously developed designs may be implemented with switching devices connected in a half-bridge arrangement. The converter may employ one or more free-wheeling diodes which are coupled in parallel to the switching devices. The free-wheeling diodes provide an alternate path for current to flow if the switching devices are turned off. Such previously designed DC-to-AC converter, however, could be problematic. For example, energy feedback through the free-wheeling diode can cause an uncontrollable dead zone in the operation of the converter. In the uncontrollable dead zone, the output voltage may not change in response to the switching—i.e., the output voltage is out of control.
FIG. 1 is an exemplary waveform diagram 100 for a power converter system, according to previously developed designs. Diagram 100 includes waveform 102 representing the voltage of the drive or control signal applied to the control terminal (e.g., gate) of a high-side switch in the half-bridge arrangement, waveform 104 representing the voltage of the drive or control signal applied to the control terminal (e.g., gate) of a low-side switch in the half-bridge arrangement, waveform 106 representing the voltage at a node between the high-side and low-side switches, and waveform 108 representing the voltage of the output AC signal of the power converter system.
As shown in diagram 100, the uncontrollable dead zone appears in the waveform 106 after the low-side switch is turned off and before the high-side switch is turned on. As further shown in diagram 100, hard switching may occur as the low-side switch turns on. As a result of the uncontrollable dead zone and hard switching, the AC output voltage of waveform 108 does not have a perfect sinusoidal form.